http://unique3phase.com/

http://unique3phase.com/001Awelder.html
And, other info.

hi from welding web member

Only thing I can see is with the home made transformer he just seperated his coils and took his ground out of the picture and basically made a floating bus which is what we call a straight power bank or can.

It is pretty neat he did this on his own but it is dangerous.

I work for a large electric company and we sometimes hang single phase transformers and do the same thing inside our transformer if all the customer needs is straight 240 power.

We use 2 bushing cans open them up remove the neutral straps/coils on the secondary side inside and float the high side neutral bushing and ya get straight 240 power but it is very uncommon to do, most of the time seeing something like this the customer is running a 3 phase welder then instead of a single transformer we hang a bank of 3 and wire it for 240 straight power, weld away.

His solution is he made a dry sump trans/can which eliminates his ground to what ever he plugs into it while making sure he does not blow his microwave off the wall, rather brilliant idea.